Electric Circuit Problem Set

Ohm's Law Homework

  1. Find the resistance of an electric light bulb if there is a current of 0.8 A and a potential difference of 120 V.
  2. What is the potential difference across a toaster of 13.7 W resistance when the current through it is 8.75 A?
  3. What is the current through an electric heater with a resistance of 38 W when the potential difference is 240 V?
  4. A light bulb uses 1.2 A when connected across a 120 V source. What power is dissipated by the bulb?
  5. What current flows through a 75 W bulb connected to a 120 V outlet? Ans: 0.625 A
  6. A 6 V battery delivers 0.5 A of current to an electric motor. What power is dissipated by the motor? How much electrical energy does it use in 5 min?

Series Circuits Homework

For each problem, draw the circuit diagram using appropriate symbols and meters.

  1. A 10 W, a 15 W, and a 5 W resistor are connected in series across a 90 V battery. Find the total resistance of the circuit. What is the current through each resistor?
  2. A 20 W and a 30 W resistor are connected in series across a 110 V potential difference. What is the total resistance of the circuit? What is the current through each resistor? What is the voltage drop across each resistor?
  3. A 3 W, a 5 W, and a 4 W resistor are connected in series across a 12 V battery. What is the total resistance of the circuit? What is the current through each resistor? What is the voltage drop across each resistor?
  4. A 60 W, a 90 W, and an unknown resistor are connected in series across a 130 V battery. An ammeter in the circuit reads 0.67 A. What is the total resistance of the circuit? What is the size of the unknown resistor? What is the power dissipated in each resistor?

Parallel Circuits Homework

  1. Three 15 W resistors are connected in parallel across a 3 V battery. Find the total resistance of the circuit. What is the total current? What is the current through each resistor?
  2. A 120 W. a 60 W, and a 40 W resistor are connected in parallel and placed across a 120 V potential difference. What is the total resistance of the circuit? What is the total current? What is the current through each resistor?
  3. A 40 W, a 8 W, and a 10 W resistor are connected in parallel across a 120 V battery. What is the total resistance of the circuit? What is the circuit current? What is the current through each resistor? What is the power dissipated?
  4. A 12 W, a 15 W. and an unknown resistance are connected in parallel. The total current of the combination is 12 A. The current across the 15 W branch is 4 A. What is the total voltage? What is the total resistance? What is the unknown resistance?

Complex Circuit Homework

  1. A 12 W resistor, a 10 W resistor, and a 15 W resistor are connected in parallel. This parallel combination is in series with a 6 W resistor and also in series with an 8 W resistor. Calculate the total resistance, the circuit current, the current through each resistor, and the voltage drop across each resistor. A 36 V battery is used.
  2. A 7 W resistor is in parallel with a 3 W resistor. This parallel combination is in series with a 5.4 W resistor. A 30 V battery is used. What is the equivalent resistance of the entire circuit? What is the total current?
  3. A 7 W, a 1 W, and a 10 W resistor are in series. This series combination is then in parallel with a 6 W resistor. The combination of the four resistors is then in series with a 10.3 W resistor. A 20 V battery is used. What is the equivalent resistance of the entire circuit? What is the total current? What is the voltage drop across the 6 W resistor? What is the current through the 1 W resistor?
  4. Calculate the total current. Calculate the voltage drop across the 36 W resistor. Calculate the voltage drop across the 16 W resistor. Calculate the current through the 48 W resistor.
  5. Calculate the total current. Calculate the voltage drop across the 8 W resistor. Calculate the voltage drop across the 12 W resistor. Calculate the current passing through the 12 W resistor.